Receiver

ABSTRACT

A receiver for receiving an analog signal having a frequency band to be digitalized has a filter unit having at least two filters for at least two receive paths, an AD converter per receive path, and digital signal processing. The filters are coupled to a common signal source in order to obtain the analog signal having the frequency band to be digitalized, and configured to divide the frequency band to be digitalized into at least two sub-bands for the at least two receive paths. The analog-to-digital converters are configured to digitalize the signals of the at least two sub-frequency bands. The digital signal processing is coupled to the at least two analog-to-digital converters in order to obtain the at least two digitalized signals and merge the at least two signals to be digitalized. The at least two filters, with regard to their filter characteristics, are configured such that the at least two sub-frequency bands have a relative bandwidth of &lt;1:2.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of copending InternationalApplication No. PCT/EP2016/073798, filed Oct. 5, 2016, which isincorporated herein by reference in its entirety, and additionallyclaims priority from German Application No. 10 2015 219 739.5, filedOct. 12, 2015, which is also incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

Embodiments of the present invention relate to a receiver for receivingan analog signal, like a high-frequency signal, having a frequency bandto be digitalized.

Such a receiver may, for example, be employed as a radio receiver ormeasuring receiver, in particular when radio or measuring signals are tobe detected in high quality over a relatively high bandwidth. In afrequency range having a great frequency width, like in the frequencyrange below 30 MHz, high powers may occur at the antenna output, inparticular with large receive antennas, depending on the conditions ofpropagation. Typically, this means a limitation of the bandwidth at theinput of the receiver. Additionally, so-called intermodulation productsof different orders may form. Second-order intermodulation products areparticularly critical.

There are already some known approaches, like using filter stages at theinput of the radio receiver. This is referred to as pre-selection andaims at preventing false reception, like at the so-called mirrorfrequency, or limiting the ingoing power. This approach is employed inboth classic analog receive architectures, like superheterodynereceivers, and receivers where intermediate frequencies are digitalized.

In high-quality receivers, the relative bandwidth of the pre-selectionfilter advantageously is selected to be smaller than 1:2. This isreferred to as the so-called sub-octave filter criterion. Using suchsub-octave filters, it is possible to reduce second-orderintermodulation products which may form in downstream stages.

In particular with low receive frequencies (like short waves of up to 30MHz) and digital receivers, pre-selection is considerably narrower thanthe real-time bandwidth which would be possible from the point of viewof a downstream analog-to-digital converter employed. This restricts theusability of the receiver considerably.

One prior-art approach is either switching the pre-selection filter incorrespondence with the desired receive frequencies or adjusting thebandwidth of the filters to the receive conditions. Switching is, forexample, discussed in EP 2 377 249 B1 using a radio signal receiver.Additionally, EP 2 191 579 B1 shows a device and a method for receivingan information signal having an information signal spectrum where thebandwidth of the filters are adjusted in correspondence with receiveconditions. Due to this adjustment or, in particular, with bandwidths ofgreater than 1:2, however, the advantages for second-orderintermodulation products vanish so that only the signal energy can bereduced. Therefore, there is need for an improved approach.

The object underlying the present invention is providing a concept whichallows receiving and digitalizing an analog signal, comprising afrequency band to be digitalized having a large bandwidth, whileavoiding or reducing intermodulation products (like of second order).

SUMMARY

According to an embodiment, a receiver for receiving an analog signalhaving a frequency band to be digitalized may have: a filter unit havingat least two filters for at least two receive paths coupled to a commonsignal source in order to obtain the analog signal having the frequencyband to be digitalized, and configured to divide the frequency band tobe digitalized into at least two sub-bands for the at least two receivepaths; an analog-to-digital converter per receive path, configured todigitalize the signals of the at least two sub-bands; and digital signalprocessing coupled to the at least two analog-to-digital converters ofthe at least two receive paths to obtain the at least two digitalizedsignals, and configured to merge the at least two digitalized signals;characterized in that the at least two filters, with regard to theirfilter characteristic, are implemented such that the at least twosub-bands have a mutual relative bandwidth of smaller than 1:2 so thatthe two filters are implemented with a change in filter bandwidthrelative to the bandwidth of a neighboring filter of the at least twofilters.

According to another embodiment, a method for receiving an analog signalhaving a frequency band to be digitalized may have the steps of:dividing the frequency band to be digitalized into at least twosub-bands by means of a filter unit having at least two filters for atleast two receive paths, wherein the at least two filters are coupled toa common signal source in order to obtain the analog signal having thefrequency band to be digitalized; digitalizing, per receive path, thesignals of the at least two sub-bands by means of an analog-to-digitalconverter per receive path; and merging the at least two digitalizedsignals by means of digital signal processing coupled to the at leasttwo analog-to-digital converters of the at least two receive paths inorder to obtain the at least two digitalized signals, characterized inthat the at least two filters, with regard to their filtercharacteristics, are implemented such that the sub-bands have a mutualrelative bandwidth of smaller than 1:2 so that the two filters areimplemented with a change in filter bandwidth relative to the bandwidthof a neighboring filter of the at least two filters.

Another embodiment may have a non-transitory digital storage mediumhaving stored thereon a computer program for performing a method forreceiving an analog signal having a frequency band to be digitalized,having the steps of: dividing the frequency band to be digitalized intoat least two sub-bands by means of a filter unit having at least twofilters for at least two receive paths, wherein the at least two filtersare coupled to a common signal source in order to obtain the analogsignal having the frequency band to be digitalized; digitalizing, perreceive path, the signals of the at least two sub-bands by means of ananalog-to-digital converter per receive path; and merging the at leasttwo digitalized signals by means of digital signal processing coupled tothe at least two analog-to-digital converters of the at least tworeceive paths in order to obtain the at least two digitalized signals,characterized in that the at least two filters, with regard to theirfilter characteristics, are implemented such that the sub-bands have amutual relative bandwidth of smaller than 1:2 so that the two filtersare implemented with a change in filter bandwidth relative to thebandwidth of a neighboring filter of the at least two filters, when theprogram runs on a computer.

Embodiments of the present invention provide a receiver for receiving ananalog signal having a frequency band to be digitalized. The receivercomprises a filter unit for at least two receive paths, ananalog-to-digital converter per receive path, and digital signalprocessing. The filter unit comprises at least two filters for the atleast two receive paths coupled to a common signal source, like anantenna, in order to obtain the analog signal having the frequency bandto be digitalized. The filters are configured to divide the frequencyband to be digitalized into at least two sub-bands for the at least tworeceive paths. The analog-to-digital converters of the at least tworeceive paths are configured to digitalize the signals of the at leasttwo sub-bands. The digitalized signals are then merged in digital signalprocessing. Here, digital signal processing is coupled to the at leasttwo analog-to-digital converters in order to obtain the at least twodigitalized signals, and configured for merging the signals in thedigital range. In addition, the at least two filters are selected,relative to their filter characteristics, such that the at least twosub-frequency bands comprise a relative bandwidth of <1:2. Here,so-called sub-octave filters or filters having a so-called sub-octavefilter characteristic may be used.

Embodiments of the present invention are based on the finding thatintermodulation products (in particular of second order) at the receiverinput can be reduced effectively by means of selecting a sufficientlynarrow filter or a plurality of sufficiently narrow filters arranged toform a filter unit. In order to make use of this effect for the entirefilter width, the individual narrow-band filters are connected to form afilter unit or to form two filter banks such that the plurality offilters covers the entire frequency band to be digitalized as far aspossible. Due to the fact that each filter is coupled directly to an ADconverter, digitalization is performed per sub-frequency band so that,subsequently, the individual sub-bands can be merged again in a digitalsignal processing stage with no losses to form an overall signal.Consequently, very good IP2 values, which evaluate the resultingsecond-order intermodulation products, can be achieved on the one hand.Secondly, the signal losses are minimal, since there are no losses, inparticular when merging.

In correspondence with further embodiments, so-called sub-octave filtersor filter having a sub-octave filter characteristic are employed asfilters. Filters having a sub-octave filter characteristic areparticularly defined in that they fulfill the so-called sub-octavecriterion, i.e. have a relative bandwidth of <1:2. This sub-octavefilter characteristic is of particular advantage with regard tointermodulation products, which will be discussed later.

In accordance with embodiments, the filter unit comprises more than two,i.e., for example, three or even more filters for three or more receivepaths. Here, the sub-frequency bands arranged directly next to oneanother may overlap partly, wherein advantageous sub-frequency bands donot overlap with a sub-frequency band therebetween. In accordance withembodiments, this is realized by grouping the plurality of filters toform two filter banks connected in parallel, wherein two filters in oneof the two filter banks having center frequencies following directly oneafter the other, with regard to the bandwidth, are configured such thatthe resulting sub-bands of the first one of the two filter banks do notoverlap, wherein a filter of the second one of the two filter banks,with regard to its center frequency, is located therebetween andconfigured to be overlapping in bandwidth with the two filters of thefirst filter bank.

Starting from an exemplary, but advantageous embodiment where therelative filter bandwidth change (i.e. change in filter bandwidthrelative to the bandwidth of the neighboring filter) for the three ormore filters of the two filter banks is approximately equal (i.e.+/−30%), the filters exemplarily are to be configured as follows. Therelative bandwidth of the filters is in a range from 1.4 to 1.6, whereinthe center frequencies increase by a factor from the range from 1.2 to1.4.

In accordance with further embodiments, the filter unit may alsocomprise a low-pass filter which comprises the lowest center frequencywhen compared to the at least two filters.

It is to be mentioned here that, in accordance with embodiments, thefilters are implemented to be purely passive elements. In accordancewith embodiments, the plurality of filters or the two filter banks herecan be connected to the signal source, like, for example, the antenna,or, generally, an input, via a common power divider. Such filter bandsmay be realized at low introduction attenuation and reactive powerdividers (attenuation factor <3 dB). It is of advantage here that activeelements upstream of the filters, for example, may be dispensed withcompletely. Electronic switches may also be omitted. Due to thesemeasures, the IP2 values can be improved further. Another advantage isthat the sensor is well protected from excess voltages by means of thepassive filter network. It is to be mentioned here also that the passivefilters for the filter unit keep the complexity thereof very small, inparticular when compared to switchable or running pre-selection.

Each receive path may optionally be equipped with an amplifier and/or anautomatic amplifier control. Here, the amplifier and/or the amplifier incombination with the automatic amplifier controller are/is arrangedbetween the filter of the receive path and the respective AD converter.

In accordance with further embodiments, the digital signal processingmay be implemented to be an FPGA which merges all the digital signals ofthe individual signal paths. In addition to digital lossless merging, itmay also optionally perform level adjustments for the individualsub-bands.

Further embodiments provide a method for receiving an analog signalhaving a frequency band to be digitalized. The method comprises thesteps of dividing the frequency band to be digitalized into at least twosub-bands, digitalizing, per receive path, the signals of the at leasttwo sub-bands, and merging the at least two digitalized signals. Thefilters for dividing are selected as has been discussed above.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be discussed in greater detailbelow referring to the appended drawings, in which:

FIG. 1 shows a block circuit diagram of a receiver having two signalpaths in accordance with a basic embodiment;

FIG. 2a shows a block circuit diagram of a receiver having a pluralityof receive paths, which are interconnected via two filter banks, inaccordance with an extended embodiment; and

FIG. 2b shows a table of exemplary values for dimensioning thecorresponding filter banks applied in embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Before discussing below in greater detail embodiments of the presentinvention referring to the appended drawings, it is to be pointed outthat equal elements or structures are provided with equal referencenumerals so that the description thereof is mutually applicable orexchangeable.

FIG. 1 shows a receiver 10, like a radio receiver, comprising a commoninput 12, digital signal processing 14 which here represents the outputof the receiver. In this embodiment, two signal paths, characterized byletters a and b, are provided between the input 12 which may exemplarilybe an antenna or, generally, a signal input or coupled to an antenna,and the digital signal processing 14.

Every signal path a and b comprises a filter 16 a and 16 b,respectively, like an analog filter 16 a and 16 b, and ananalog-to-digital converter 18 a and 18 b, respectively. The filters 16a and 16 b together form the filter unit 16. All the filters 16 a and 16of the filter unit 16 are connected to the common input 12 or commonnode point 12.

The effect of this is that each signal path a and b receives the samesignal 22 having the full frequency band from the common node point 12.The signal applied to the input is an analog signal comprising afrequency band 22 to be digitalized. This frequency band 22 to bedigitalized is divided by the filters 16 a and 16 b, or the filter unit16, into the sub-frequency bands 26 a and 26 b at the output of thefilters 16 a and 16 b. Consequently, the analog-to-digital converters 18a and 18 b do no longer receive the full frequency band 22 to bedigitalized, but only the individual sub-frequency bands 26 a and 26 b.Each of this sub-bands 26 a and 26 b is then digitalized by means of thespecific AD converter 18 a and 18 b (cf. signals 27 a and 27 b).

In the downstream digital signal processing 14, the sub-bands 26 a and26 b can be merged again completely or with no gaps therebetween. Themethod of merging is known in the art and described, for example, in EP2 377 249 B1 or EP 2 191 579 B1. The (digital) combined signal 29 whichcomprises the entire signal band to be digitalized, is then passed on toa further unit (not illustrated) in the combined form. Evaluating thedata does not have to take into consideration filter boundaries, sincethe frequency bands were merged before with not gaps therebetween in thesignal processing. Here, a conventional network or also an opticalnetwork can be used, as is illustrated using the arrow at the output ofthe digital signal processing 14.

Here, filtering by the filter unit 16 takes place such that thesub-frequency bands 26 a and 26 b comprises a relative bandwidth of<than 1:2, that it fulfill the sub-octave filter criterion. Thebackground of this is that intermodulation products will form if atleast two frequency bands in a system are processed in parallel, whereinthere will be non-linear transfer functions. If two differentfrequencies, like the at least two center frequencies, for example, areguided through the receiver, the result will be second-orderintermodulation products:

f₁+f₂ and f₁−f₂.

In order to prevent the intermodulation products from summing up, thecorresponding filter bandwidths are selected to be relatively narrow,wherein relatively narrow is to be related to the center frequency ofthe respective sub-band. It has shown that a relative filter bandwidth,which corresponds to the sub-octave characteristic, i.e. smaller than aratio of 1:2, like 1:1.5 or 1:1.35, for example, is suitable to weakeninput signals outside this frequency range of interest such that thesecond-order intermodulation products thereof, within the passband, arereduced to the same extent. A relative filter bandwidth of 1.6, forexample, or, generally, a range from 1.4 to 1.6 or 1.2 to 1.8 fulfillsthis sub-octave criterion. The center frequencies of each filterincrease from one filter to the next of the filter unit 16. In general,the relative bandwidth is selected to be smaller than 1:2, whereas thecenter frequencies increase in a corresponding absolute way.

Subsequently, starting from these basic embodiments having two receivepaths a and b, an embodiment having an overall number of 12 receivepaths is shown below.

FIG. 2a shows the receiver 10′ comprising an input 12′ and a digitalsignal processing stage 14. An overall number of 12 signal paths A to Lis provided between the input 12′ and the digital signal processingstage 14.

The 12 signal paths a to l of the receiver 10′ comprise the filters 16 ato 16 l, respectively, of the filter stage 16, and the analog-to-digitalconverters 18 a to 18 l, respectively. In this embodiment, amplifierelements 17 a to 17 l are provided on the input side relative to theanalog-to-digital converters 18 a to 18 l between the filters 16 a to 16l and the analog-to-digital converters 18 a to 18 l. These serve foradjusting the signal to be output by the respective filters 16 a to 16 lin the respective sub-bands relative to their amplitude so that aneffective analog-to-digital conversion can be performed by theanalog-to-digital converters 18 a to 18 l. In order to efficientlyregulate modulation of the respective amplifier elements 17 a to 17 l,in correspondence with further embodiments, an automatic amplifiercontroller 15 a to 15 l may be connected upstream of the respectiveamplifiers 17 a to 17 l.

On the input side, the filters 16 a to 16 l of the filter stage 16(filter unit) are all connected to a node point which here is realizedby a power divider 121′. The power divider 121′ is coupled with itsinput to the antenna 12 a′. Looking at it from the other side, thismeans that the power divider 121′ is connected between the antenna inputand the filter unit 16 which, as is illustrated here, may consist ofseveral filter banks. The power divider 121′ ensures sufficientisolation (like 20 dB or more, for example) between the ports for thedifferent filter banks 16_1 and 16_2, which will be discussed below ingreater detail. The background here is that the different filter banks16_1 and 16_2 are not to influence each other.

As has already been indicated, in accordance with embodiments (and as isillustrated here), on the output side, the power divider 121′ comprisestwo outputs (ports), wherein the filters 16 a, 16 c, 16 e, 16 g, 16 iand 16 k (first filter bank 16_1) are coupled in at a first output,wherein the filters 16 b, 16 d, 16 f, 16 h, 16 j and 16 l (second filterbank 16_2) are supplied by the second output of the power divider 12 t′.The background of this is that, in accordance with embodiments, thefilter unit 16 is subdivided into two different filter banks 16_1 and16_2, wherein the transmission characteristics of the respective secondfilters 16 a, 16 c, 16 e, 16 g, 16 i and 16 k, i.e. the filters of thefirst filter bank 16_1, and the filters 16 b, 16 d, 16 f, 16 h, 16 j and16 l, i.e. the filters of the second filter bank 16_2, are not mutuallyoverlapping, whereas the transmission characteristics of the filters,which are directly adjacent to one another, belonging to the twodifferent filter banks 16_1 and 16_2, like 16 ab or 16 bc or 16 cd, forexample, etc., are arranged to be overlapping, as will be discussedbelow referring to the table of FIG. 2b . Due to the fact that thefilters 16 a, 16 c, 16 e, 16 g, 16 i and 16 k and the filters 16 b, 16d, 16 f, 16 h, 16 j and 16 l of a filter bank 16_1 and 16_2 (i.e. thefilters 1/3/5/7/9/11 and 2/4/6/8/10/12 of FIG. 2b ) do not overlap, itis made possible that the filters 16 a to 16 l on the input side arecoupled in a purely reactive manner with low losses only.

In accordance with embodiments, the input of the power divider 12′ orthe common node point of the filter bank 16 may be coupled to theantenna 16 a in a switchable manner via a switch 12 s′, wherein acalibration source 12 k′ is provided at a second input of the switch 12s′. The background of this is that the paths a to l and also the digitalsignal processing 14 can be calibrated with a known test signal usingthe calibration source. Advantageously, but not necessarily, theadjustment determined from the calibration takes place in the digitalsignal processing 14.

As has been discussed above, the digital signal processing 14, whichmay, for example, be realized as an FPGA (or alternatively ASIC or insoftware) is configured to combine the output signals of theanalog-to-digital converters 18-18 l and optionally compensate forelement-caused differences which were determined by means of thecalibration source 12 k′. These differences may, for example, be storedin an additional memory 14 s′ for calibration data. In accordance withembodiments, the digital signal processing 14 may be configured tocompensate for level differences caused by the automatic amplifiercontroller (cf. reference numbers 15 a to 15 l and 17 a to 17 l). Inaccordance with further embodiments, the FPGA is programmed orcontrolled via a controller 14 c′.

In accordance with embodiments, the entire desired receive range isreceived by means of the receivers 10′ discussed above via the signalpaths a to l, wherein the entire receive range, like 0 to 30 MHz, forexample, is divided into the 12 filters. In the example of a receiverange from 0 to 30 MHz or, generally, from 0 to x MHz, in accordancewith embodiments, the first filter, here the filter 16 a, may beimplemented not to be a sub-octave filter (i.e. not belonging to thefilter bank 16 defined above), but a low-pass filter. The dimensioningof the other 11 filters or, generally, the dimensioning of the 12filters, will be discussed below referring to FIG. 2 b.

FIG. 2b shows a possible dimensioning of a filter unit for a frequencyrange from 0 to 30 MHz, wherein the start and stop frequencies areindicated for each filter (cf. filters no. 1 to 12). It is alsoillustrated which filter bank the respective filters 1 to 12 belong to.As has already been discussed before, filter no. 1 is implemented to bea low-pass filter. All the other filters comprise a relative bandwidthof wave 1.6 to one another. The sub-octave criterion is thus met well,except for filter band no. 1. Since the frequency boundaries increasefrom one filter to the next each only by a factor of wave 1.31, theresult is sufficient overlapping of neighboring filters, i.e. filters ofdifferent filter bands (cf. ab).

Even when, in the above embodiments, two filters were assumed in theeasiest case, wherein one filter bank is formed by one filter, or 12filters, wherein six filters each belong to one filter bank, it is to bepointed out that the number may vary in correspondence with the desiredfrequency width to be digitalized. This means that filter units havingan overall number of eight filters or even 14 filters or an odd numberof filters are conceivable.

Even when the above embodiments were discussed in particular inconnection with a device or the receiver 10, 10′, it is to be pointedout that further embodiments refer to a corresponding method. The methodcomprises the steps of:

-   -   Dividing the frequency band to be digitalized into at least two        sub-bands by means of a filter unit comprising at least two        filters for at least two receive paths, wherein the at least two        filters are coupled to a common signal source in order to obtain        the analog signal having the frequency band to be digitalized.    -   Digitalizing, per receive path, the signals of the at least two        sub-bands by means of an analog-to-digital converter per receive        path.    -   Merging the at least two digitalized signals by means of digital        signal processing which is coupled to the at least two        analog-to-digital converters of the at least two receive paths        in order to obtain the at least two digitalized signals.

The filters are implemented in correspondence with the abovedimensioning rules.

Although some aspects have been described in the context of a device, itis clear that these aspects also represent a description of thecorresponding method, such that a block or element of am device alsocorresponds to a respective method step or a feature of a method step.Analogously, aspects described in the context with or as a method stepalso represent a description of a corresponding block or detail orfeature of a corresponding device. Some or all of the method steps maybe executed by (or using) a hardware apparatus, like, for example, amicroprocessor, a programmable computer or an electronic circuit. Insome embodiments, some or several of the most important method steps maybe executed by such an apparatus.

Depending on certain implementation requirements, embodiments of theinvention can be implemented in hardware or in software. Theimplementation can be performed using a digital storage medium, forexample a floppy disk, a DVD, a Blu-Ray disc, CD, ROM, PROM, EPROM,EEPROM or FLASH memory, a hard drive or another magnetic or opticalmemory having electronically readable control signals stored thereon,which cooperate or are capable of cooperating with a programmablecomputer system such that the respective method will be performed.Therefore, the digital storage medium may be computer-readable.

Some embodiments according to the invention include a data carriercomprising electronically readable control signals, which are capable ofcooperating with a programmable computer system such that one of themethods described herein will be performed.

Generally, embodiments of the present invention can be implemented as acomputer program product with program code, the program code beingoperative for performing one of the methods when the computer programproduct runs on a computer. Nowadays, bandwidths around 30 MHz can bein-line-processed in real time on efficient PCs.

The program code may, for example, be stored on a machine-readablecarrier.

Other embodiments comprise the computer program for performing one ofthe methods described herein, wherein the computer program is stored ona machine-readable carrier.

In other words, an embodiment of the inventive method is, therefore, acomputer program comprising a program code for performing one of themethods described herein, when the computer program runs on a computer.

A further embodiment of the inventive methods is, therefore, a datacarrier (or a digital storage medium or a computer-readable medium)comprising, recorded thereon, the computer program for performing one ofthe methods described herein.

A further embodiment of the inventive method is, therefore, a datastream or a sequence of signals representing the computer program forperforming one of the methods described herein. The data stream or thesequence of signals may, for example, be configured to be transferredvia a data communication connection, for example via the Internet.

A further embodiment comprises processing means, for example a computer,or a programmable logic device, configured to or adapted to perform oneof the methods described herein.

A further embodiment comprises a computer having installed thereon thecomputer program for performing one of the methods described herein.

A further embodiment according to the invention comprises a device or asystem configured to transfer a computer program for performing at leastone of the methods described herein to a receiver. Transmission can beperformed electronically or optically. The receiver may, for example, bea computer, a mobile device, a memory device or the like. The device orsystem may, for example, comprise a file server for transferring thecomputer program to the receiver.

In some embodiments, a programmable logic device (for example afield-programmable gate array, FPGA) may be used to perform some or allof the functionalities of the methods described herein. In someembodiments, a field-programmable gate array may cooperate with amicroprocessor in order to perform one of the methods described herein.Generally, in some embodiments, the methods may be performed by anyhardware device. This can be universally applicable hardware, such as acomputer processor (CPU), or hardware specific for the method, such asASIC.

While this invention has been described in terms of several embodiments,there are alterations, permutations, and equivalents which will beapparent to others skilled in the art and which fall within the scope ofthis invention. It should also be noted that there are many alternativeways of implementing the methods and compositions of the presentinvention. It is therefore intended that the following appended claimsbe interpreted as including all such alterations, permutations, andequivalents as fall within the true spirit and scope of the presentinvention.

1. A receiver for receiving an analog signal comprising a frequency bandto be digitalized, comprising: a filter unit comprising at least twofilters for at least two receive paths coupled to a common signal sourcein order to acquire the analog signal comprising the frequency band tobe digitalized, and configured to divide the frequency band to bedigitalized into at least two sub-bands for the at least two receivepaths; an analog-to-digital converter per receive path, configured todigitalize the signals of the at least two sub-bands; and digital signalprocessing coupled to the at least two analog-to-digital converters ofthe at least two receive paths to acquire the at least two digitalizedsignals, and configured to merge the at least two digitalized signals;wherein the at least two filters, with regard to their filtercharacteristic, are implemented such that the at least two sub-bandscomprise a mutual relative bandwidth of smaller than 1:2 so that the twofilters are implemented with a change in filter bandwidth relative tothe bandwidth of a neighboring filter of the at least two filters. 2.The receiver in accordance with claim 1, wherein the at least twofilters are sub-octave filters and/or comprise a sub-octave filtercharacteristic.
 3. The receiver in accordance with claim 1, wherein thefilter unit comprises two filter banks comprising at least one filtereach, wherein the at least two filters of the two filter banks dividethe frequency band to be digitalized into the at least two sub-bandssuch that the sub-bands of the at least two filters of the two filterbanks overlap partly.
 4. The receiver in accordance with claim 1,wherein the filter unit comprises a total number of at least threefilters for at least three receive paths so that the frequency band tobe digitalized is dividable into at least three sub-bands for the atleast three receive paths.
 5. The receiver in accordance with claim 4,wherein the at least three filters comprise such a filter characteristicthat the change in filter bandwidth thereof is equal with +/−30%,wherein the center frequency of the respective bandwidth increases overthe at least three filters of the filter bank.
 6. The receiver inaccordance with claim 3, wherein two filters in one of the two filterbanks comprising directly successive center frequencies, with regard tothe bandwidth, are configured such that the sub-bands of one of the twofilter banks do not overlap, wherein a filter of the other one of thetwo filter banks, with regard to its center frequency, is locatedtherebetween.
 7. The receiver in accordance with claim 1, wherein therelative bandwidth is in a range from 1.4 to 1.6, and wherein the centerfrequency increases by a factor in the range from 1.2 to 1.4.
 8. Thereceiver in accordance with claim 1, wherein the filter unit comprisesan additional low-pass filter which, when compared to the at least twofilters, comprises the lowest center frequency.
 9. The receiver inaccordance with claim 1, wherein the at least two filters of the filterunit comprise exclusively passive elements.
 10. The receiver inaccordance with claim 1, wherein the at least two filters of the filterunit and/or the two filter banks are connected to the common signalsource via a common power divider.
 11. The receiver in accordance withclaim 1, wherein the at least two filters of the filter unit and/or thetwo filter banks are connected to a common antenna as a common signalsource or are connected to the common antenna via a common powerdivider.
 12. The receiver in accordance with claim 2, wherein the numberof filters of the filter unit is selected such that the entire frequencyband to be digitalized is covered by the sub-bands.
 13. The receiver inaccordance with claim 1, wherein the digital signal processing comprisesan FPGA.
 14. The receiver in accordance with claim 1, wherein mergingtakes place in the digital signal processing in a lossless way.
 15. Thereceiver in accordance with claim 1, wherein each of the at least twosignal paths between the analog-to-digital converter and the respectivefilter comprises an automatic amplifier controller and/or an amplifier.16. A method for receiving an analog signal comprising a frequency bandto be digitalized, comprising: dividing the frequency band to bedigitalized into at least two sub-bands by means of a filter unitcomprising at least two filters for at least two receive paths, whereinthe at least two filters are coupled to a common signal source in orderto acquire the analog signal comprising the frequency band to bedigitalized; digitalizing, per receive path, the signals of the at leasttwo sub-bands by means of an analog-to-digital converter per receivepath; and merging the at least two digitalized signals by means ofdigital signal processing coupled to the at least two analog-to-digitalconverters of the at least two receive paths in order to acquire the atleast two digitalized signals, wherein the at least two filters, withregard to their filter characteristics, are implemented such that thesub-bands comprise a mutual relative bandwidth of smaller than 1:2 sothat the two filters are implemented with a change in filter bandwidthrelative to the bandwidth of a neighboring filter of the at least twofilters.
 17. A non-transitory digital storage medium having storedthereon a computer program for performing a method for receiving ananalog signal comprising a frequency band to be digitalized, comprising:dividing the frequency band to be digitalized into at least twosub-bands by means of a filter unit comprising at least two filters forat least two receive paths, wherein the at least two filters are coupledto a common signal source in order to acquire the analog signalcomprising the frequency band to be digitalized; digitalizing, perreceive path, the signals of the at least two sub-bands by means of ananalog-to-digital converter per receive path; and merging the at leasttwo digitalized signals by means of digital signal processing coupled tothe at least two analog-to-digital converters of the at least tworeceive paths in order to acquire the at least two digitalized signals,wherein the at least two filters, with regard to their filtercharacteristics, are implemented such that the sub-bands comprise amutual relative bandwidth of smaller than 1:2 so that the two filtersare implemented with a change in filter bandwidth relative to thebandwidth of a neighboring filter of the at least two filters, when theprogram runs on a computer.